It has long been known that Streptococcus mutans is closely involved in the decayed teeth or caries.
Moreover, the periodontosis is related to the abnormal proliferation of periodontal disease-related microorganisms within periodontal pockets. In this connection, known examples of such periodontal disease-related microorganisms include Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Bacteroides forthythus, Prevotella intermedia, Fusobacterium nucleatum, Capnocytophaga spp., corroding organisms (Wolinella spp., Campylobacter gracilis, and Eikenella corrodens), Eubacterium spp., and Treponema spp. and it has been known that these microorganisms each take part in the periodontal disease to a variety of degrees. Among these, the initial two kinds of or the first and second microorganisms (Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis) have been regarded as important in the disease.
In addition, Candida albicans has been known as a causal bacterium for the “thrush (candidal stomatitis)” and there have recently been proposed some opinions which point out the close correlation between the abnormal proliferation of Candida spp. within the oral cavity and the periodontosis.
Incidentally, it has long been known that the extract from Sasa albo-marginata has an antimicrobial activity. For instance, there have been reported such antimicrobial activities as those against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli, which are known as causal bacteria for infectious diseases of wound and those against Helicobacter pylori known as a causal bacteria for the gastric ulcer. The inventors of this invention have already found that if such a Sasa extract is used in a concentration (as expressed in terms of the solid content) ranging from 1 to 10% by mass, preferably 2 to 8% by mass and more preferably 3 to 7% by mass, various effects can be obtained, which have never been achieved by the conventional extract having a low concentration. For instance, it has an improving effect for, for instance, atopy; it shows significant antipruritic effect; and it has likewise considerably improved wound-healing effect (see, for instance, WO 02/07745).
However, it has not yet been known whether or not the Sasa extract has the antimicrobial activity effective for any kind of bacteria and it has not likewise generally been known that an extract derived from a natural source, which shows an antimicrobial activity against bacteria, also shows an antimicrobial activity against fungi such as Candida spp.